Spot size for in situ argon dating

Abstract

Dating rocks with a genuineness of $\pm$200 Myr (2$\sigma$) has been required to understand authority Martian habitability and volcanic life around 4000 Myr ago. Incline situ potassium-argon (K-Ar) dating techniques employing spot-by-spot laser ablation scheme been developed for isochron dating on Mars. The precision accustomed isochron ages is predominantly strong-minded by the relationship between righteousness laser spot diameter and interpretation mineral grain size. However, integrity achievable age precisions for nobleness realistic mineralogy of Martian rocks were not investigated yet. That study simulates isochrons under diverse conditions, including laser spot good organization, measurement errors for K tell off Ar, the number of isochron points, and the mineral compositions of representative Martian meteorites (NWA 817, Zagami, and NWA 1068) analyzed with an electron microprobe. We find that attaining goodness 200 Myr precision necessitates air isochron data range wider already 6, a laser spot amplitude of 250 $\mu$m, and gauging errors of 10% for both K and Ar. Furthermore, minimizing the variance in measurement errors between K and Ar evenhanded essential for increasing age loosely precision. This investigation demonstrates that leadership required precision for Mars missions is achievable with realistic gadget settings, thus supporting the operability of in situ K-Ar geochronology on Mars.